Gyroscopic instrument and indicator therefor



Jan. so, 1945. R Q HOLT I 2,368,221

GYROSCOPIC INSTRUMENT AND INDICATOR THEROR Filed July l5, 1943 INVENTOR Y PLINY G. HOLT, B

ATTORNEY Patented Jan. 30, 1945 GYROSCOPIC INSTRUMENT AND INDICATOR THEREFOR Pliny G. non, United states Navy Application July 15, 1943, Serial No. 494,885

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 9 Claims.

This invention relates to improvements in gyroscopic flight instruments such as, for example, the gyroscopic artificialhorizon.

In articial horizons used in military aircraft,

A it is gustomary to provide the same with.- means for holding the gyroscope and its associated girn, bal system in a fixed or caged position when the instrument is not being used. Such caging is particularly needed when the aircraft is engaged in acrobaties. Unless the gyroscope 'is caged during aerobatics, it will tumble or precess when it reaches its operating limits and cause severe loads on the gimbals and bearings of the instrument. Furthermore, when an instrument of this kind has tumbled, steady level flight for ten or more minutes is often necessary before the instrument returns to a normal indieating position.

By the use of the caging dew'ce, the pilot can fix the instrument in a zero position i. e. a position indicating level flight before going into aerobatcs.

However, it often happens that the pilot forgets to uncage the gyroscope gimbal system when normal flight is resumed with the result that the pilot is misled by the normal fiightvindication of the instrument into believing that the aircraft is in a position of normal flight whereas the aircraft may actually be flying in a dangerous attitude. j

It is therefore the principal object of this invention to provide a means for positively indicating to the pilot when an instrument of `the class described is caged or uncaged. y

A specific object is to provide an indication for a pilot or other user when the gyroscopic element of a gyro operated instrument is caged. which includes a target or other suitable indicator .that is moved from a hidden position when the gyroscopic element is uncaged into the open eld portion of the face of the instrument (where the instruments indication is viewed) when th gyroscopic element is caged.

Another specific objectis to provide a gyroscope caging indicator in accord with the preceding object in which the indicating member occupies a position across at least a portion of the instruments indication when the gyroscope 4is panying drawing which illustrates a preferred embodiment of the invention.

In the drawing, in which like reference characters are used to indicate like parts in the several views presented:

Fig. 1 is a plan view of an artificial horizon instrument constructed according to my invention, the outer case being shown in section;

Fig. 2 is a side elevation of the instrument shown in Fig. 1, the outer case also being shown in section;

Fig. 3 is a front view of the instrument showing the position of the target type indicator when the instrument is in the uncaged position; and,

Fig. 4 is also a front view showing the position of the indicator when the instrument is in a caged position.

Referring now 'to the drawing; the artificial horizon instrument is shown as enclosed within an outer air tighrt case I having a forward window II through which the horizon bar I2 is visible. The rotor of the gyroscope (not shown) is mounted within a casing I3 by means of a gimbal ring I4 pivoted on the fore and aft axis I5-I5 Within the case I0. The casing I3 is pivoted within fthe gimbal ring I4 on a transverse axis Iii-I6. For centralizing or caging the gyroscope, there are provided a pair of rings I8 and I9 rotatably mounted within the case I0 and having gear teeth and 2'I, respectively on the inner edges thereof. These teeth mesh with a gear 22 which is secured to a stub shaft 23 which is journalled on the side of the case I0 and provided with a beveled pinion gear 24 on the outer end thereof.

A knob 25 secured to a shaft 26, when pulled outwardly against the opposing action of a spring 2l, meshes another |beveled gear 28 secured on the shaft 26 with the pinion gear 24. Thus rotation of the knob 25 when gears 24 and 28 are in mesh effects rotation of caging ring I8 in one direction and rotation of caging ring I9 in an opposite direction. The ring I8 is provided with a finger 29 which projects inwardly towards the caging ring I9. A similar finger (not shown) projects from the caging ring I9 towards caging ring I8. An L shaped pin 30 projects from the gyroscope casing I3 through an annular slot 3I in the gimbal ring I4 and extends 'from a point at one side of the axis I6I6 so that when the pin is engaged, it locks or cages the gyroscope casing I3 about both axes I5I5` and IB-IG, bringing it toa neutral position. The -pin 30 may be used as the pin normally employed to move the horizon bar I2 up and down,the pin 30 passing through a slot 32 in the long lever 33 which is pivoted on the gimbal ring I4 at 34. When the gyroscope is caged, the bar I2 will indicate normal, level flight.

carried by ring IB and the similar iinger carriedA by ring I9 grasp the pin 30 between them and x it securely in position. For a more complete description of the construction and operation voi the caging apparatus, reference may be had to A U. S. Patent No. 2,018,735 issued October 29, 1935.

2,368,221 f f p la ing; means cooperable with said caging meansfor indicating to said user the position of said caging means, last said means comprising a. mem- "ber movable into said window portion and posi- From the foregoing description, it willbe obl vious that it is impossible for the pilot to tell from looking at the instrument whether or not the device is caged or uncaged. Therefore in order-that the pilot may have a positive indication of the condition of the device, a target35 is provided. This target which may, if desired, be inscribed with suitable indicia such as Caged is the down turned portion of a, bracket 36, the latter being secured by rivets. to. the caging ring I 8. The arrangement is such that when the gyroscope is fully uncaged and therefore in an operative position, the target 35 is hidden from view, being disposed behind a tongue portion 3l of the face 38, the tongue portion being used to support a reference aeroplane 39 which with the horizon bar I2 is viewed by the pilot in the open eld portion of the face 38 as in Fig. 3.

When, however, the knob 25 is rotated, thereby rotating the caging rings I 8 and I9 towards a caging position, the target 35 will likewise be turned from the position in Fig. 3 to that in Fig. 4 Where it will be in full view of the pilot. In

Fig. 4, the target 35 is shown in the positionit occupies when the gyroscope is fully caged. However, it will be evident that since the tongue 31 is relatively narrow, the target 35 will also be visible to the pilot in all positions of the caging rings I8, I9 except the position in which the gyroscope is fully uncaged.

In conclusion, it will be evident that my invention provides a means whereby the pilot can tell at a glance whether or not the horizon instrument is caged or uncaged. It will likewise b e-evident that various changes and modifications in the present embodiment may occur to and be made by others skilled in the art Without departing from the spirit and scope of my invention as defined in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having thus fully described my invention, I claim:

1. In a gyroscopic instrument including acasing having a window portion through which the instruments indication is viewed, a gyroscope mounted within said casing and caging means operable by a user for locking said gyroscope to prevent movement thereof relative to said casing; means cooperable with said caging'means forindicating to-said user the position' of said caging means, last said means being 'visible to said user in said window portion when said gy;-- roscope is caged but hidden from view when-said gyroscope is fully uncaged. l .'1

`2. In a gyroscopic instrument including a casing having a window portionthrough which'the tioned across at least a portion of the instrument indication when said gyroscope is caged.

3. In a gyroscopic artificial horizon instrument including a casing, a gyroscope mounted within said casing, caging means operable by a user for locking said gyroscope to prevent movement thereof relative to said casing and a face including an open iield portion for observing the horizon bar of said instrument and a tongue portion projecting into saideld portion; target means cooperable wth said caging means for indicating to said user the position of said ging means, said target, means being hiddenfrom view behind said tongue portion -when said. gyroscope is. fully uncaged but movable into the eld portion of said face upon operation of said caging means. e

4. In a gyroscopic artificial horizon instrument including a casing, a gyroscope universally pivoted thereon on two normally horizontal axes, a .face including an open field. portion for observing the horizon bar of vsaid instrument and a tongue portion projecting into. said eld portion, a pair of rings. rotatably mounted within said casing, means operable by a user for rotating said rings, and means carried by said rings for engaging said gyroscope to cage the latter about both of said axes as said rings are rotated; target means carried by one of said rings for indicating to said user the position of said rings, said target means being hidden from view behind the tongue porton of said face when said gyroscope is fully uncaged but movable into the eld portion of saidface upon rotation of said 'rings towards a caging position.

5. In a gyroscopic instrument including a casing, a face having an open eld portion in which the instruments indicationhis vieweda gyroscope gimballed within said casingLand caging vmeans for locking said gyroscope; ,means ,cooperable with said caging means for indicating the position of 'said caging means, lastsaid means being visible in said field portion when said gyroscope is at least partially caged but hidden 4from view when said gyroscope is uncaged. V v n 6. The invention defined in claim 5 wherein last said means l( :ornprises a'target member,A l

7. In a gyroscopic instrument includinga casing, a face having an open field portion in which the instruments indication'is viewed, a gyroscope gimballed within said casing, and Acaging means for locking said gyroscope; means for indicating the position of said caging means, last said means being movable with operation of said caging means into said'eld portion when said gyroscope is at least partially caged. 1

8. The invention defined in claim 7 wherein last said means comprises av target member.

9. Tne'invennen defined in eieirn r1 wherein last said means is positioned across at least .a portion ofthe instruments indication whenfsaid gy-A roscope is caged'. e' A' e 

